A plurality of Thin Film Transistors (TFTs) are integrated in a TFT array substrate to drive the pixels in a Liquid Crystal Display (LCD) or Organic Light-Emitting Diode (OLED) display panel, for displaying an image on the display panel in combination with periphery driving circuitry. Accordingly, the TFTs, which are switches for controlling the light emitting, are critical for implementing the image display, and are directly involved in the development trend of the display panel. However, in a TFT array substrate of the display panel in the prior art, the area of a storage capacitor is overlapped with agate insulator layer, leading to a thick structure formed by various stacked dielectric layers, so that the capacitance of the storage capacitor is accordingly decreased and is insufficient, and the parasitic capacitance is increased, thus affecting the image display quality.